Railway vehicle



July 27, 1937. 4A. HUGUENiN RAILWAY VEHICLE `Filed June 29, v1935 2 Sheets-Sheet 1 lhwentor Gttornegs July 27, 1937.

A. vHUGUENIN RAILWAY VEHICLE Filed June 29, 1955 2 Sheets-Sheet 2 Bnventor Cttornegs Patented July 27, 1937 UNITED STATES RAILWAY VEHICLE` Albert Huguenin, Zurich, Switzerland Application Junefzs, 1935, serial No. 29,148

In Switzerland July 12, 1934 2 Claims.

'Ihis invention relates to railway Vehicles, and particularly to means for steering bogies or single axles in response to curvature of the track.

Steering devices of this general class are already known, and it has even been proposed to displace the .axles angularly about vertical axes vfor steering purposes in passing through curves, and even transition curves,'by means of a servo- .motor. Thus angular displacement is effected automatically and in a degree suited to the curvature of the track, so that the reactions between the wheel flanges and the rails are kept to a minimum.

Vehicle suspensions of this general type require that the vehicle frame be pivoted to the trucks on vertical axes on the -center line of the frame. The trucks may be of the bogie type or of the single-axle (two wheeled) type.

The present invention relates to this class of devices and contemplates the use of an hydraulic servo-motor mounted on the vehicle frame, connected with the truck or trucks to steer the same, and controlled by feelers cooperating with the rails and laterally displaced by curvature thereof. The purpose of the invention is to ensure a rapid, powerful and accurate response of the servo-motor to the indications of the feelers.

In developing a satisfactory device of this class a number of factors'must be` taken into consideration. The spacing of al set ,of feelers from the truck whose angular position it controls is limited. Even if the feelers be located `'beneath-the outermost end of the car frame, the distance cannot exceed the overhang of the car beyond the axle. From this limited spacing it follows that only a limited period of time is available for the performance of the steering func-tionand this period diminishes as 'vehicle speed increases. Consequently in order to secure satisfactory steering at high speeds and on relatively sharp curves, the response of the servomotor tothe indications of the feelers must be rapid and po-werful.

To meet these requirements, it is necessary to adopt special designs 'for the connections between the servo-motorv and its control valve, and these features are the principal subjectfmatter of the present invention. Important features are the mounting of the control valve' withinV the servo-motor piston, thevalve seatbeing formed in this piston, the construction ofthe valveand its seat in such a way that-the valvehas negative lap (clearance) on its controlling edgesin the neutral position, andthe use of flow passagesof (c1. l10s-16s) large cross section andv shortv length, to the end that resistance `to flow and consequent loss of pressure head on the hydraulic medium shall be lo-w. Shortness of the flow passages is secured by the formation of these passages inthe servo# motor piston and large cross section is secured by designing the passages to occupy the maximum portion of the cross section of the piston consistent with the provision of necessary wall thickness and necessary stiffening ribs. v

Negative lap of the `valveand the use of large, short, iiow passagespermit constant vcirculatory flow of the' hydraulicmedium, which causes a sharp temporary increase in the delivery pressure of the pump which develops the hydraulic pressure, whenever thevalve is displacedfrom its neutral position with respect tothe piston. This sharp increase Vin pressure entails instant and powerful response of. the piston of the servomotor, in shiftingto reestablish the neutralrelation between the pistonfand valve. In this way the requirement for rapidia'nd 'precise response is met completely by the use/of; an extremely simple mechanism. The pump:. op`erates continuously under a moderate load, which increases momentarily when the position of fthe truck is being shifted.

An illustrative embodiment ofthe inventionwll now be described in connection with the accom- ,30

panying drawings, in which,-

Fig. 1 is a vertical section on the line l-l of Fig. 4 showing the servo-motor and portions of its control mechanisnL y Fig. 2 is an elevation looking from the end of the car with partsbroken away toshow the-construction. Y i Q Fig. 3 isa side elevation showing portions of the truck and of thevehicle frame.

Fig. 4 is a plan Viewrpartly in section.

Fig. 5 is an enlarged vertical axial section through the servo-motor andits control valve.

Figs. 6, 7 and 8 aretransverse sections taken, respectively, on the lines VI-VI VII- VII vand VIII-VIII ofFig. 5.

v Fig. 9 is a diagram showing in plan the guiding around a curve of a railroad vehiclehaving two swiveled trucks, each equipped with a single axle. u i

The feelers take the form of two-.small rollers I, and are mountediat. each endof the vehicle,

one pair for eachof the two trucks.' Each 'roller `I is journaledin the end of ahorlzo'ntal rod 2,

which is hingedonga horizontal axis'tof the lower end ofa corresponding ver-tical'shaft Sgfswiveled in bearings 3', xed in relation to the vehicle frame A and illustrated as mounted in the housing of the servo-motor hereinafter described. Springs 2 urge the rods 2 downward tol hOld the rollers I in contact with the rail despite upward and downward motion of the vehicle frame relatively to the rail (such motion being permitted by the usual spring suspension, not shown).

LeverY arms 4 are xed on the upper ends or shafts 3 and the two arms are each elastically connected to the upper end of a lever arm 6 by compression links each comprising a cylinder 8 with coacting piston 5 and an interposed coil compression spring 5. It follows that the arm 6 responds to the mean of the indications of the two related rollers I. This arrangementensures that the flanges on rollers I engage the rails ,continuously and also provides for the permissible variations in gage which on the continent of Europe may amount to 1 centimeter (gage limits being from 1435 .to 1445 millimeters). The effect is to ensure prompt and accurate response under all conditions. Y Lever arm 6 is xed on a horizontal rock shaft, whichA carries fixed to it a vsecond arm '9. Arm 9 is connected by link `Il) to oneA arm/of a twoarmedlever II which is fulcrumed at I-2. The other arm of lever Il is operatively connected with the end of the control or pilot valve I3 of the servo-motor indicated generally by the numeral I4 .applied -to its housing.

t A'distinguishing characteristic of the control valve I3 is the vnegative lap (clearance) of its control edges I6 and -I`| with respect to the coacting annular port 2'| (see Fig. 5). Edge I6 controls discharge and edge I'I controls admission so that in neutral position admission and discharge passages are partially open. The housing I4 ofthe servo-motor is rigidly 40 secured to the frame A of the vehicle as shown and forms a cylinder for the piston I5, as clearly indicated in Fig. 5. vThe piston I5 is formed with a lug projecting through a slot in the cylinder I4 (see Fig. 4) and this lug has a ball and socket connection'z with a projection I9 carried by the swiveled truck I8. Thus the truck will be turned by motion` of the piston. Y

. A pump 2| is mounted on the end of the 'servomotor housing I4 and delivers the necessary hydraulic pressure iiuid, preferably oil. 'The pump is driven by motor '22 through gearing 23, draws oil from a sump 24 (Fig. 1) and delivers it under pressure to the working space 25 in which the small end of piston I5 is exposed (see Fig. 5). From yworking space 25 the -oil enters passage 26 in piston I5 (see Figs. 6 and `'7) and is delivered to the annular chamber 26. l

- With the parts in the neutral position of Fig. 5, the oil under pressure flows past the control edge I1 to annular chamber 2'I and thence past control edge I6 to chamber l23 `within piston I5. Chamber 28 is in constant free communication with sump 24 by way of axial 'bore 29 in valve I3, port '30 in piston I5, and passage 3|. Chamber 2'I is connected by passage 32 with Working space 33 in which the other larger -end of piston I5 is exposed. A tail sleeve through which valve I3 `works reduces the `e'fective Aarea Aof this end vof the piston, so that the eiective areas of the two ends are Aproperly coordinated. Denning direction with reference to Fig. 5, the left end-of piston :|.5iszexposed at all times to the discharge pressure developed yby pump 2I. This pressure is intensied if valve AI3 ,moves to :the right so that 4edge I'I throttles flow. The

right end of piston I5 is subject to a pressure which varies as the result of changes of relative position of Valve I3 and piston I5 causing variable throttling of supply at II with simultaneous inversely variable throttling of discharge at I6.

Obviously the piston I5 tends to follow the valve I3 and shifting of the valve after a neutral relation has been established produces sharp increases of effective pressure on the piston with attendant rapid response of the piston. Since chamber 28 Yis freely open to discharge, valve I3 is balanced. The channels 26, 32 and 29 are of large cross section and short length, so as to avoid .pressurelosses and ensure quick action.

The device operates as follows:

The lvalve I3 follows the mean indication of the tworelated rollers I, remaining in its central position on straight track. In entering a curve the rollers I move laterallyrelatively to the car, shift- Iing lever 6 and the connected valve I3.. Piston II-5 `necessarily follows valve I3 and shifts the truck I8. Consequently, with reference to Figs. 4 and 5,1the control valve I3 will be moved to the right. The result thereof is that the control edge I 'I will be covered and the oil under Vpressure will be prevented from flowing out of the channels 26 into the :annular channel 21 While oil under pressure may ilow freely out of the chamber 33 past the control edge I6 through the channel 29 and the opening 30 to the discharge opening 3|. Consequently, the delivery pressure of the pump 2| and the pressure in the chamber 25 undergo a temporary increase which ensures, in conjunction with the great-volume delivered, a very sudden and rapid movement of the servo-motor piston I5 to the right.. When the lever 6 is swung out to the left, .the control valve I3 will move to the left and the edge I6 will be covered so that `the pressure in the chamber 33 now undergoes an intermittent increase which results in a sudden rapid movement of the servo-motor piston I5 to the left.

If it be desired to guide two-axle bogies, an operative connection of the bogie frame (rotatable on a vertical axis) with the servo-motor piston I5, must be established in the same manner as described with reference to the axle frame I9, whilethe construction Yor design of the axle guide proper remains the same as hereindescribed.

What is claimed is,-

1. The combination of a railway vehicle comprising a. frame mounted on trucks which have swiveled connection with said frame, said trucks including rail-engaging supporting wheels; at least one hydraulic servo-motor including a cylinder and coacting double-acting piston connected to turn a'corresponding truck relatively to the vehicle frame, said piston being formed with supply and discharge `flow passages for the hydraulic liquid, and a ported valve seat with the ports of which said passages communicate, said passages being characterized by short `length and large cross sectional area; a pilot valve mounted in said valve seat, controlling the ports thereof and characterized 'by negative lap on a supply and a discharge port a circulating pump arranged to supply pressure directly to said servo-motor; and a ieeler 'mechanism lmounted on said frame and -coacting with the track to respond to curvature voi the track, said feeler mechanism being connected to actuatesaidpilot valve.

2. The combination Aof a railway Vehicle comprising av `frame mounted -on trucks which have swiveled connection with said frames, said `trucks 'including' rail-engaging supporting wheels; at

least one hydraulic servo-motor including a cylinder and a coacting double-acting differential piston connected to turn a corresponding truck relatively to the vehicle frame, said piston being formed with a ported valve seat and short oW passages of large transverse area leading from each working space of the servo-motor to corresponding ports in said seat, and a discharge passage of large capacity; a balanced pilot Valve in 1u Said seat and shiftable therein to throttle at relatively inverse rates communication between said working spaces and communication with said discharge passage, said valve being characterized by negative lap; a circulating pump for supplying liquid under pressure directly to the smaller Working space; and a feeler mechanism mounted on said frame and coacting With the track to respend to curvature of the track, said feeler mechanism being connected to actuate said pilot valve.

ALBERT HUGUENIN. 

